I've always found this a little misleading. When restoring, I sometimes do it folder at a time so not to overload things and sometimes I cancel the restore. This is flagged as an error:
So two observations here - firstly, not really an error but let's assume that stays. If you then start another restore in the same session, the error count stays. So you have to remember that the reason the error is shown is because you cancelled it. It says "Restore complete with error", hence my "misleading" or certainly slightly confusing.
I'm not sure what to suggest to improve this. Maybe error count should be cleared when you start another restore. Or maybe say "Total errors: 1, last operation: 0".